Concealed metastatic lung carcinoma presenting as acute coronary syndrome with progressive conduction abnormalities.

A 70-year-old diabetic woman with recent onset of cough was admitted to the emergency room for acute chest pain with evidence of T-wave abnormalities in the V2 through V6, L1, and aVL leads (Figure 1A). Her coronary arteries were angiographically normal, and her troponin I was elevated at 0.3 g/L. Twodimensional echocardiography revealed a hypertrophic left ventricle without kinetic abnormalities. Three weeks later, the patient was readmitted for chest pain and a complete left bundle-branch block on 12-lead ECG (Figure 1B) with a peak troponin I of 0.429 g/L. To exclude a myocarditis, a cardiac magnetic resonance (CMR) was performed. On early scout images, diffuse multiple nodules with irregular epicardial borders were evident (Figure 2A–2C), which were also present on CMR T1 cine balanced images, indicating an irregular tissue composition (Movies I and II in the online-only Data Supplement). A moderate pericardial effusion was also detected. On T2-weighted images, the nodules presented a signal intensity higher than skeletal muscle (Figure 3A). First-pass contrast sequences showed inhomogeneous perfusion at the level of intramyocardial nodules (Movie III in the online-only Data Supplement). On late gadolinium CMR imaging, an inhomogeneous and reduced contrast uptake was noted, diffusely involving the ventricular myocardium besides the nodules (Figure 3B). These features were in keeping with an abnormal myocardial tissue composition,1,2 not resulting from myocardial edema, thus ruling out myocarditis. During the same examination, a right pulmonary mass was also detected and better defined on computed tomography (Figure 4). A transbronchial biopsy was then performed, revealing a lung carcinoma (Figure 5). One week later, the patient developed a complete atrioventricular block (Figure 1C), and she died 3 days later. Postmortem definitely ruled out coronary artery disease and provided a diagnosis of lung adenosquamous cell carcinoma with multiorgan metastases and pericardial effusion. Multiple firm white masses were already visible on external examination of the heart. On serial transverse sections, corresponding to equivalent CMR postcontrast sequences images, the nodules consisted of neoplastic tissue proliferation with variable amounts of myocardial necrosis (Figure 6). At higher magnification, the metastatic tumor was composed of irregularly shaped glands with marked cytological atypia infiltrating the myocardium and spreading to the epicardium (Figure 7). Although primary cardiac tumors are extremely uncommon, secondary tumors are not.3 In a recent postmortem survey of 7289 malignant neoplasms, an incidence of 9.1% of heart metastases was found.4 The highest rate of heart metastasis was reported in pleural mesothelioma (48.4%), melanoma (27.8%), lung adenocarcinoma (21%), undifferentiated carcinoma (19.5%), lung squamous cell carcinoma (18.2%), and breast carcinoma (15.5%). To the best of our knowledge, this is the first case describing a concealed lung carcinoma presenting like acute coronary syndrome as a result of the diffuse infiltration of the myocardium, as detected in vivo by CMR and then confirmed by postmortem pathology examination. Moreover, the extension of the neoplastic infiltration to the basal septum, as detected by CMR, explains the progressive conduction system involvement, eventually leading to complete atrioventricular block. The multiparametric tissue characterization provided by CMR helps differential diagnosis with more common causes of troponin release such as myocardial infarction or myocarditis.